JP4531489B2 - Charger and image forming apparatus - Google Patents

Description

  The present invention relates to a charger for controlling a charged state of an image carrier such as a photosensitive member or an intermediate transfer member by a corona discharge means, and an image forming apparatus such as a copying machine, a printer, and a facsimile using the charger.

  In an electrophotographic image forming apparatus that forms a toner image by exposing and developing a charged photoreceptor, it is important to uniformly charge the photoreceptor in order to obtain a high quality image. As a method of charging the photosensitive member, there is a method of charging without contacting, in addition to a method of charging by contacting the photosensitive member. For example, a charger for charging without contacting the photoconductor generates corona discharge from a discharge wire arranged with a certain gap from the photoconductor. By using corona discharge that charges the surface to be charged with spread, the photoconductor can be uniformly charged to form high-definition and high-quality images, while sub-substances such as ozone and nitrogen oxide (NOx) are generated. The

  The ozone generated by the discharge oxidizes the surface of the photoreceptor and deteriorates other parts, so that the quality of the image to be formed is impaired. NOx reacts with moisture to produce nitric acid, and further reacts with metal to produce metal nitrate. Since nitric acid and metal nitrate have high resistance in a low-humidity environment, if they adhere to the discharge wire, the discharge becomes unstable, causing uneven charging of the photoconductor and degrading the image quality.

  Patent Document 1 includes a discharge means provided along the longitudinal direction of the discharge wire behind the discharge wire and provided with a cover body that can be opened and closed at the opening, and an ozone suction hole. By generating an air current that is sufficient to suck only the ozone gas, it is possible to discharge the ozone gas from the discharge means without sucking up the residual toner on the photoconductor, thereby preventing the photoconductor from being deteriorated by the ozone gas. An image forming apparatus has been proposed.

  Patent Document 2 discloses an image forming apparatus for preventing uneven charging by forming a ceramic film on the surface of a charged wire discharge to prevent fine particles from adhering to the charged wire electrode and preventing the charged wire electrode from being consumed. Has been proposed.

  Patent Document 3 discloses an image forming method in which a shield case of a corona charger is heated to remove moisture from the shield case, thereby preventing resistance from changing due to an electrolyte attached to the shield case and causing uneven charging. A device has been proposed.

  Patent Document 4 discloses a voltage applied to the charging device by heating the atmosphere around the covering member or the covering member by heating means provided in the covering member of the charging electrode to reduce the humidity of the discharge space portion of the charging device. An image forming apparatus that obtains a uniform and stable discharge that does not affect the reduction of ozone, the amount of ozone generation, and external humidity conditions has been proposed.

  Patent Document 5 proposes a corona discharge device that heats and decomposes ozone and NOx at a location close to the generation source by heating the discharge wire from 400 ° C. to 300 ° C. with a heating means. In Patent Document 5, convection is generated by a humidity gradient between the surface of the discharge wire and the surroundings to prevent stagnation of discharge products, and stable discharge is maintained by maintaining the surface of the discharge wire at a high temperature and keeping it clean. it can.

  However, as disclosed in Patent Document 5, if the temperature of the discharge wire is about 400 ° C. to 300 ° C., NOx cannot be decomposed sufficiently. When the temperature of the discharge wire is high, if the temperature distribution of the discharge wire is not uniform, only a part of the discharge wire contributes to the decomposition of the discharge products, or a large amount of current is used to keep the whole temperature above a certain temperature. Need to flow. When the current density of the discharge wire becomes excessive, the surface of the discharge wire is deformed or the discharge wire is disconnected due to electromigration.

Furthermore, when the discharge wire is heated to a high temperature, the discharge characteristic is changed due to thermal expansion, and the distance from the photoreceptor changes. In order to absorb the slack of the discharge wire due to thermal expansion, if the tension is applied to the discharge wire at a high temperature with an elastic member such as a spring, the discharge wire is easily deformed and disconnected, and the wire is very thin. It is difficult to control the variation without load, and heat is dissipated from the elastic member, resulting in uneven temperature distribution of the discharge wire.
JP-A-8-44259 JP-A-8-202121 JP 2001-22158 A JP 2001-109229 A JP 2001-312122 A

  An object of the present invention is to provide a charger capable of stably discharging a discharge wire while maintaining a uniform temperature distribution, and an image forming apparatus including the charger.

The charger of the present invention includes a support member, a discharge wire, a discharge power source, and a heating unit. The support member stretches the discharge wire close to the member to be charged, the discharge power source applies a voltage between the discharge wire and the member to be charged, and the discharge wire discharges between the member to be charged. Wake up. The heating means includes a heating wire and a heating power source that generates heat by passing an electric current through the heating wire, and the heating wire supports the heating unit and the discharge wire that generate heat in a region relatively close to the discharge wire support member. A heating unit that generates heat near a region relatively far from the member is heated , and a region relatively close to the support member of the discharge wire is heated at a higher temperature than a region relatively far from the support member of the discharge wire. The heating wire has a resistance value of a heating part that generates heat close to a region relatively close to the support member of the discharge wire to be larger than a resistance value of a heating unit that generates heat close to a region relatively far from the support member. It is good to be formed.

It is preferable that a discharge wire heating power source for generating heat by supplying a current to the discharge wire is provided, and the discharge wire has an area having a spiral shape in the vicinity of the support member and a linear area relatively far from the support member.

Heating wire, the surface of the heating unit that generates heat in proximity to a relatively distant area from the support member of the heating unit and the discharge wire generates heat in proximity to the relatively close region to the support member of the discharge wire is generated by the discharge It is good to coat | cover with the catalyst material layer which decomposes | disassembles a substance. The surface of the discharge wire may be covered with a catalyst material layer that decomposes a substance generated by the discharge. The inner surface of the shield case that covers the discharge wire may be covered with a catalyst material layer that decomposes a substance generated by the discharge.

The image forming apparatus of the present invention includes any one of the above chargers .

  According to the first aspect of the present invention, both ends of the discharge wire, in which heat is likely to diffuse through the support member, can be easily heated from the central portion, the temperature distribution of the entire discharge wire is made uniform, and the discharge voltage is stabilized. The voltage can be lowered.

  According to the second aspect of the present invention, furthermore, both ends of the discharge wire, in which heat is easily diffused through the support member, can be easily heated from the central portion, the temperature distribution of the entire discharge wire is made uniform, and the discharge voltage is stabilized. The discharge voltage can be lowered.

  According to the third aspect of the present invention, the discharge wire can be prevented from being deteriorated due to current, and the discharge characteristics can be stabilized for a long time. Further, when the discharge wire thermally expands and contracts, the discharge wire moves in a direction orthogonal to the linear region. The discharge characteristics can be maintained by reducing the displacement and maintaining the distance between the discharge wire and the object to be charged, and by absorbing the thermal expansion and contraction of the discharge wire that has become high temperature in the spiral region, It is possible to prevent disconnection by preventing mechanical stress from being applied to a portion that becomes brittle at high temperatures.

  According to invention of Claim 4, the substance produced | generated by discharge can be decomposed | disassembled near a generation source, a spreading | diffusion can be prevented, and generation | occurrence | production of a secondary production | generation substance can be prevented. According to the fifth aspect of the present invention, the substance generated by the discharge can be decomposed near the generation source to prevent diffusion, and the generation of secondary generation substances can be prevented. According to the sixth aspect of the present invention, the substance generated by the discharge can be decomposed near the generation source to prevent diffusion, and the generation of secondary generation substances can be prevented.

According to the seventh aspect of the invention, it is possible to form an image while performing stable discharge at a low discharge voltage with a uniform temperature distribution on the discharge wire .

  As shown in the configuration diagram of FIG. 1, the image forming apparatus 1 according to the first embodiment includes an optical writing unit 2, a photosensitive member 3, a charger 4, a developing device 5, a charge eliminating lamp 6, a paper feeding unit 7, and a transfer unit. An electrode for separation 8, an electrode for separation 9, a discharge lamp 10, a cleaning device 11, a conveyor belt 12, a fixing device 13, and a control unit 14. Note that the image forming apparatus is a device that uses a charger in an image forming process such as charging before forming an electrostatic latent image on an image bearing member such as a photosensitive member or an intermediate transfer member, or removing electricity after forming a toner image. Other configurations such as a printing apparatus, a copier, and a fax machine may be used.

  The optical writing unit 2 includes an image processing unit 20, a laser driver unit 21, a semiconductor laser 22, a polygon mirror 23, and a scanner motor 24. The image data input by the image processing unit 20 is subjected to signal processing by shading correction, gradation correction by γ conversion, halftone reproduction by multi-value processing, and the like, and then input to the laser driver unit 21. The laser driver unit 21 turns on the semiconductor laser 22 in accordance with the image data signal-processed by the image processing unit 20, and irradiates the polygon mirror 23 rotated by the scanner motor 24 with the laser beam, thereby changing the rotation direction of the photosensitive member 3. The laser beam is scanned in the vertical direction.

  The photosensitive member 3 as a member to be charged that rotates in the rotation direction 31 is uniformly negatively charged by a charger 4 that is supplied with a negative high voltage current and corona discharges, and is emitted from a semiconductor laser 22. The electrostatic latent image is formed by the above scanning, developed by the developing device 5 to visualize the toner image, and the negative charge remaining on the surface is erased by the charge eliminating lamp 6.

  The paper feed unit 7 includes a paper feed cassette 70, a paper feed roller 71, a registration sensor 72, and a registration roller 73. The recording paper sent from the paper feeding cassette 70 by the rotation of the paper feeding roller 71 is temporarily stopped while being detected by the registration sensor 72 and abutting against the registration roller 73, and the timing is adjusted to the image developed on the photosensitive member 4. Thus, the photosensitive roller 3 is reached by rotating the registration roller 73. The toner image formed on the photoconductor 3 is transferred to the recording paper sent to the photoconductor 3 by the transfer electrode 8 supplied with a positive high voltage from the high voltage generator. The recording paper on which the toner image has been transferred is discharged from the photoreceptor 3 by being discharged by the separation electrode 9 to which an AC high voltage is supplied from a high voltage generator.

  After the transfer, the remaining charge is removed by irradiation of the charge removal lamp 10, and the slightly remaining toner is scraped off by the cleaning device 11 to prepare for the next image formation. The recording paper on which the toner image is transferred and separated from the photoreceptor 3 is sent to the fixing device 13 by the conveying belt 12 and is pressed and heated while passing between the upper roller and the lower roller of the fixing device 13. As a result, the toner image is fixed and discharged. The control unit 14 controls the overall operation of the image forming apparatus 1.

  As shown in the cross-sectional view of FIG. 2, the charger 4 includes a discharge wire 40, a support member 41, a shield case 42, a discharge power source 43, and a heating unit 44. The discharge wire 40 is stretched in the direction perpendicular to the direction in which the surface of the photoconductor 3 moves close to the photoconductor 3, and both ends are supported by the support members 41. The support member 41 is formed of an insulating material, and is fixed inside a shield case 42 formed so as to cover the discharge wire 40 except for the surface on the photoconductor 3 side. The discharge power supply 43 applies a high voltage between the discharge wire 40 and the photoconductor 3 to generate a corona discharge between the discharge wire 40 and the photoconductor 3.

  The heating unit 44 includes a heating wire 441, three adjustment resistors 443, and a heating power source 444. The heating wire 441 formed of a heat generating material such as nichrome or tantalum is disposed adjacent to the discharge wire 40 at a distance of about 5 to 100 μm and close to a region relatively far from the support member of the discharge wire 40. A region 442a in the central part that generates heat and a region 442b and a region 442c at both ends that generate heat close to the region relatively close to the support member of the discharge wire 40 are configured. The adjustment resistor 443a is connected in parallel to the central region 442a of the heating wire 441, and the adjustment resistors 443b and 443c are connected in parallel to the region 442b and the region 442c at both ends of the heating wire 441, respectively. The resistance value Rb of the adjustment resistor 443b at both ends and the resistance value Rc of the adjustment resistor 443c are larger than the resistance value Ra of the adjustment resistor 443a at the center. The heating power supply 444 applies a voltage to both ends of the heating wire 441, causes the heating wire 441 to generate Joule heat by the flowing current, and raises the temperature of the adjacent discharge wire 40 by raising the temperature of the atmosphere. By separating the discharge wire 40 and the heating wire 441, a material suitable for heat generation can be used as the heating wire 441.

  When the discharge wire 40 is heated, the air in the vicinity is warmed and the pressure in the vicinity of the discharge wire 40 is reduced. According to Paschen's law V = P × d, which shows that the value obtained by multiplying the pressure P in the vicinity of the discharge wire 40 by the distance d between the discharge wire 40 and the photoreceptor 3 becomes the discharge voltage, the temperature of the discharge wire 40 is increased. When the pressure P in the vicinity of the discharge wire 40 is lowered, the discharge power V is lowered, so that the generation amount of ozone or the like can be reduced.

  The voltage applied to the region 442b and the region 442c near both ends of the heating wire 441 is higher than the voltage applied to the region 442a in the central portion of the heating wire 441, and the vicinity of both ends of the heating wire 441 is higher than the central portion. Therefore, the vicinity of both ends of the adjacent discharge wire 40 is more easily heated than the central portion. As shown in FIG. 3A, the temperature of the entire discharge wire 40 is increased as shown in FIG. 3B by heating both ends of the discharge wire 40 where heat is easily diffused through the support member 41 from the center. Distribution can be made uniform. By making the temperature distribution of the discharge wire 40 uniform, the discharge can be stabilized, and a high discharge voltage required for performing discharge in a low temperature region of the discharge wire 40 becomes unnecessary, and the discharge power source The capacity of 43 can be reduced. In addition to dividing the heating wire 441 into three regions, other numbers may be used as long as they are plural.

  According to this image forming apparatus 1, it is possible to form an image stably with a low discharge voltage with a uniform temperature distribution of the discharge wires.

  The heating wire 451 included in the charger 450 of the second embodiment has a uniform resistance value as a whole, and as shown in the cross-sectional view of FIG. Are arranged to be far away. For example, the distance d1 at both ends is 5 to 100 μm, and the distance d2 at the center is 2 to 10 times the distance d1 at both ends. Of the discharge wire 40, both end portions closer to the heating wire 451 are more easily heated than the center portion far from the heating wire 451. Other configurations are the same as those of the first embodiment.

  The temperature distribution of the entire discharge wire 40 can be made uniform by making it easier to heat both ends of the discharge wire 40 where heat is easily diffused through the support member 41 from the center. By making the temperature distribution of the discharge wire 40 uniform, the discharge can be stabilized, and a high discharge voltage required for performing discharge in a low temperature region of the discharge wire 40 becomes unnecessary, and the discharge power source The capacity of 43 can be reduced.

  The distance between the heating wire 451 and the discharge wire 40 is linearly increased from the end toward the center, and the distance is changed in multiple stages by dividing the heating wire 451 into a plurality of regions. Alternatively, the distance may be changed according to the temperature distribution of the heating wire 451 based on the fact that the amount of heat conduction is inversely proportional to the square of the distance between the heating wire 451 and the discharge wire 40.

  As shown in the cross-sectional view of FIG. 5A, the heating wire 461 included in the charger 460 of the third embodiment is linearly stretched along the rotation axis direction of the photoconductor 3 in the vicinity of the photoconductor 3. Both ends are supported by the support member 41, and the diameter d3 of the central portion as shown in the sectional view of FIG. 5B is the diameter of the both ends as shown in the sectional view of FIG. Greater than d4. For example, the diameter d3 at the center is made about 1.2 to 2.5 times larger than the diameter d4 at both ends. If the central part and both ends of the heating wire 461 have the same diameter, the temperature of the both ends of the discharge wire 40 that causes thermal diffusion to the support member 41 is lower than that of the central part, whereas the heating wire 461 is heated. The diameter of both ends of the wire is made smaller than the diameter of the central portion, the resistance value of both ends is made larger than the resistance value of the central portion, the Joule heat generation at both ends of the heating wire 461 is increased from the central portion, and the heat capacity is small. By making it easy to raise the temperature of both ends, both ends of the discharge wire 40 are easily heated, and the temperature drop due to thermal diffusion to the support member 41 is compensated to make the entire discharge wire 40 have a uniform temperature distribution. Can do. Other configurations are the same as those of the first embodiment. If the resistance value at the center of the heating wire 461 is made smaller than both ends to reduce the amount of Joule heat generation, and the heat capacity at both ends is made smaller than that at the center, for example, as shown in FIG. Another heating wire 463 may be uniformly wound around only the central portion of the uniform heating wire 462.

  The temperature distribution of the entire discharge wire 40 can be made uniform by making it easier to heat both ends of the discharge wire 40 where heat is easily diffused through the support member 41 from the center. By making the temperature distribution of the discharge wire 40 uniform, the discharge can be stabilized, and a high discharge voltage required for performing discharge in a low temperature region of the discharge wire 40 becomes unnecessary, and the discharge power source The capacity of 43 can be reduced.

  The charger 470 of the fourth embodiment includes a discharge wire 471, a support member 41, a shield case 42, a discharge power source 43, and a discharge wire heating power source 472 as shown in the cross-sectional view of FIG. The discharge wire 471 is stretched close to the photoreceptor 3 in a direction perpendicular to the direction in which the surface of the photoreceptor 3 moves, and both ends are supported by the support member 41. It has 473 and has a straight line region 474 between the spiral regions 473 at both ends. The support member 41 is fixed to a shield case 42 formed so as to cover other than the surface of the discharge wire 471 on the photosensitive member 3 side. The discharge power source 43 applies a high voltage between the discharge wire 471 and the photoconductor 3 to generate a corona discharge between the discharge wire 471 and the photoconductor 3. The discharge wire heating power supply 472 applies a voltage to both ends of the discharge wire 471 and causes the discharge wire 471 to generate Joule heat by the flowing current. The spiral region 473 in which the discharge wires 471 are close and dense due to the spiral structure increases in resistance value due to concentration of generated heat and rises in temperature, thereby increasing Joule heat generation and further increasing in temperature. The discharge wire 471 can be heated more easily, and the entire temperature of the discharge wire 471 can be made uniform by compensating for a decrease in temperature due to thermal diffusion to the support member 41 at both ends of the discharge wire 471. Other configurations are the same as those of the first embodiment.

  The temperature distribution of the entire discharge wire 471 can be made uniform by making it easier to heat both ends of the discharge wire 471 through which the heat is easily diffused through the support member 41 from the center. By making the temperature distribution of the discharge wire 471 uniform, the discharge can be stabilized. When the temperature distribution of the entire discharge wire 471 is uniform, the resistance value of the entire discharge wire 471 is larger than the case where there is a region where heat is locally generated at a high temperature in the central portion of the discharge wire 471, and the entire discharge wire 471 is increased. Since the current density required to raise the temperature of the discharge wire 471 to a predetermined temperature is reduced, there is a margin in the actual current density with respect to the current density allowed for the discharge wire 471, preventing deterioration of the discharge wire 471 due to current. Discharge characteristics can be stabilized for a long time. If the temperature distribution of the discharge wire 471 is made uniform, the discharge voltage can be lowered, so that the capacity of the discharge power supply 43 can be reduced.

  When the discharge wire 471 undergoes thermal expansion and contraction, the spiral region 473 changes in the radial direction and the linear region 474 changes in a direction along the straight line, so that the displacement in the direction perpendicular to the linear region 474 can be reduced, and the discharge Discharge characteristics can be maintained by maintaining the distance between the wire 471 and the photoreceptor 3. By absorbing the thermal expansion and contraction of the discharge wire 471 at a high temperature by the spiral region 473, it is possible to prevent mechanical stress from being applied to the portion of the discharge wire 471 that has become brittle at a high temperature, thereby preventing disconnection.

  In the production of discharge wires, impurities in the wire material, temperature at the time of drawing, annealing, temperature distribution, tension, rotation, twisting, winding, surface polishing, etc., manufacturing conditions, surface scratches, crystal alignment, grain boundary Due to precipitates, etc., discharge wires that generate heat at high temperatures tend to cause linear thinning and twisting depending on the crystal plane angle, etc., and discharge wires that generate excessive heat cause crystal defects and impurities to crystal grain boundaries. Due to potential factors of precipitation and torsional residual stress, disconnection is likely to occur due to slippage at the grain interface. For example, a discharge wire 475 having a tungsten crystal grain boundary as shown in FIG. 8A is likely to be disconnected due to a slip or the like generated at the crystal grain interface as shown in FIG. By absorbing the thermal expansion and contraction of the discharge wire 475 that has become high temperature in the spiral region 473, mechanical stress is prevented from being applied to a portion of the discharge wire 475 that has become brittle at a high temperature, thereby preventing disconnection.

The vibration can be suppressed because the thermal expansion and contraction are relaxed in the spiral region 473, and the discharge characteristics can be stabilized because the resonance due to the external vibration is not amplified. In the case where the tension is maintained with a larger tension, it is desirable that both ends of the discharge wire 471 be a spring-like spiral region 476 in which a plurality of spirals are stacked as shown in FIG. Furthermore, the charger of the first embodiment to the third embodiment is further provided with a discharge wire 471 having a spiral region 473 at both ends supported by the support member 41 and a discharge wire heating power source, thereby further increasing the discharge wire. The temperature distribution of the entire 471 can be made uniform.

In the charger of the fifth embodiment, a discharge wire 481 having a catalyst material layer 482 on the surface is used in the chargers of the first to fourth embodiments as shown in the sectional view of FIG. The catalyst material layer 482 on the surface of the discharge wire 481 is composed of a noble metal element, an alkali oxide, an alkaline earth oxide, a rare earth oxide, a composite material thereof such as Pt, Pd, Rh, TiO ₂ , SnO ₂ in a liquid phase. It is formed into a thin film with a thickness of about nanometer to micrometer by a method such as plating, electrodeposition, electrostatic coating, vapor deposition, sputtering, and CVD.

  By providing the catalyst material layer 482, ozone, NOx, SOx, etc. generated in the vicinity of the discharge wire 481 can be decomposed near the generation source, so that diffusion can be prevented. Generation of product substances can be prevented. In addition, the catalytic action is easily activated by heating the catalyst material layer 482 with a heating wire. In the first to fourth embodiments, since the discharge wire can be made to have a uniform temperature distribution, the discharge wire can be heated to about 500 ° C., and the activity of the catalyst material layer can be increased. Since it has a catalyst material layer, the discharge wire may be made of tungsten, or may be made of stainless steel, nichrome, tantalum or the like that is suitable as an electrothermal material.

  Note that in order to increase the efficiency of the catalytic action in the catalyst material layer 482, it is desirable to increase the surface area by making the surface of the catalyst material layer 482 uneven or have a porous structure, and to prevent peeling due to uneven discharge. It is desirable to make the uneven shape and the porous structure dense.

  Since the temperature of the heated discharge wire 481 decreases from the inside to the outside, the catalyst material layer 482 has a laminated structure of an inner metal oxide ZnO layer and an outer noble metal Pd layer, and a comparison around 400 ° C. It is better to decompose NOx with the metal oxide ZnO, which has a high catalytic efficiency at a high temperature, and to decompose ozone with the noble metal Pd, which has a high catalytic efficiency at a relatively low temperature around 350 ° C.

  In addition, a catalyst material layer may be formed on the surface of the heating wire of the first to third embodiments, or a catalyst material layer may be formed on the inner surface of the shield case 42 where the temperature rises to some extent due to width radiation. Good. When the amount of ozone, NOx, SOx, etc. generated in the vicinity of the discharge wire is large, the ozone, NOx can be decomposed by heating the shield case or decomposing the discharge product against the catalyst material layer of the shield case with a fan. , SOx can be actively decomposed.

  As shown in the configuration diagram of FIG. 11, the charger of the sixth embodiment is similar to the charger 4 of the first embodiment, in which the first environment measurement sensor 491, the second environment measurement sensor 492, and the heating control unit 493 are used. And have. The first environmental measurement sensor 491 measures the temperature and humidity near the discharge wire 40. The second environmental measurement sensor 492 measures the temperature and humidity outside the image forming apparatus. The heating control unit 493 increases the temperature of the discharge wire 40 when ozone is measured by the first environment measurement sensor 491 when a low temperature and dry state is measured, or when a high temperature and humidity state is measured. When decomposition of NOx or the like is promoted and a low temperature and high humidity state or a high temperature and dry state is measured, the temperature of the discharge wire 40 is lowered.

  The discharge characteristics can be stabilized by controlling the temperature of the discharge wire 40 depending on the environment in the vicinity of the discharge wire 40. At the start of the image forming apparatus in which the environment in the vicinity of the discharge wire 40 is likely to change suddenly, the environment inside and outside the image forming apparatus is measured in detail by the first environment measuring sensor 491 and the second environment measuring sensor 492, thereby discharging. The discharge characteristics can be stabilized by controlling the temperature of the wire 40. The environment outside the image forming apparatus may be measured in advance by the second environment measurement sensor 492, and a change that the outside environment gives to the environment in the vicinity of the discharge wire 40 may be predicted in advance. For example, the external temperature decreases. In this case, the heating power supply 444 is controlled by the heating control unit 493 by predicting a decrease in the internal temperature, and the temperature of the heating wire 441 is increased to increase the temperature of the discharge wire 40 or the external temperature is increased. In that case, the temperature of the discharge wire 40 may be decreased by predicting an increase in the internal temperature. The heating control unit 493 may intermittently supply power to the heating wire 441 at development cycle intervals, and a power-saving image forming apparatus can be configured by heating the discharge wire 40 with a minimum amount of heat generation. .

  The environmental measurement sensor measures temperature and humidity, and also measures moisture density, gas, pressure, airflow, hydrocarbon concentration, etc., and the environment near the discharge wire 40 and the environment outside the image forming apparatus. May be measured in advance, and the environment outside the image forming apparatus may be measured in advance to predict the change in the environment in the vicinity of the discharge wire 40 in advance.

  Since the discharge wire 40 can have a uniform temperature distribution, the decomposition efficiency of ozone and NOx is high, and it is not necessary to heat the casing having a large heat capacity to assist the decomposition of ozone and NOx, thereby suppressing the thermal influence on the photoreceptor. Note that the concentrations of ozone and NOx having different decomposition temperatures are measured for each component by the environmental measurement sensor 491 and the environmental measurement sensor 492, and based on the measurement results, the heating control unit 493 decomposes the decomposition temperature of ozone and NOx having a high concentration. Further, when the temperature of the discharge wire 40 is controlled, it can be decomposed more effectively, and since the temperature of the discharge wire 40 is kept uniform, ozone and NOx can be efficiently decomposed at the respective decomposition temperatures. The temperature distribution of the entire discharge wire 40 can be made uniform by making it easier to heat both ends of the discharge wire 40 where heat is easily diffused through the support member 41 from the center. By making the temperature distribution of the discharge wire 40 uniform, the discharge can be stabilized, and a high discharge voltage required for performing discharge in a low temperature region of the discharge wire 40 becomes unnecessary, and the discharge power source The capacity of 43 can be reduced.

1 is a configuration diagram of an image forming apparatus. It is a block diagram of the charger of 1st Embodiment. It is a figure which shows the relationship between the position in a discharge wire, and temperature. It is a block diagram of the charger of 2nd Embodiment. It is the block diagram of the charger of 3rd Embodiment, and sectional drawing of a discharge wire. It is the block diagram of the other charger of 3rd Embodiment, and sectional drawing of a discharge wire. It is a block diagram of the charger of 4th Embodiment. It is a figure which shows the disconnection generation factor of a discharge wire. It is an enlarged view of the spiral region of the discharge wire having a plurality of spirals. It is sectional drawing of the discharge wire of 5th Embodiment. It is a block diagram of the charger of 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Image forming apparatus, 2; Optical writing unit, 3; Photoconductor, 4; Charger, 5; Developer
6; static elimination lamp, 7; paper feeding unit, 8; transfer electrode, 9; separation electrode,
10; Static elimination lamp, 11; Cleaning device, 12; Conveying belt, 13; Fixing device,
14; control unit, 20; image processing unit, 21; laser driver unit,
22; semiconductor laser, 23; polygon mirror, 24; scanner motor,
31; rotating direction; 40; discharge wire; 41; support member; 42; shield case;
43; discharge power source, 44; heating unit, 70; paper feed cassette, 71; paper feed roller,
72; registration sensor, 73; registration roller, 441; heating wire,
442; area, 443; adjusting resistor, 444; heating power source, 450; charger,
451; heating wire, 460; charger, 461; heating wire, 462; heating wire,
463; heating wire, 470; charger, 471; discharge wire,
472; discharge wire heating power source, 473; spiral region, 474; linear region,
475; discharge wire, 476; spiral region, 481; discharge wire, 482; catalyst material layer,
491; 1st environmental measurement sensor, 492; 2nd environmental measurement sensor, 493; Heating control part.

Claims (7)

A support member, a discharge wire, a discharge power source, and heating means;
The support member stretches the discharge wire in the vicinity of an object to be charged,
The discharge power source applies a voltage between the discharge wire and the object to be charged,
The discharge wire causes a discharge with the object to be charged,
The heating means includes a heating wire and a heating power source that generates heat by passing a current through the heating wire,
The heating wire has a heating part that generates heat in the vicinity of a region relatively close to the support member of the discharge wire and a heating unit that generates heat in a region relatively far from the support member of the discharge wire. The charger is characterized in that a region relatively close to the support member of the discharge wire is heated at a higher temperature than a region relatively far from the support member of the discharge wire.   The heating wire has a resistance value of a heating part that generates heat in the vicinity of a region relatively close to the support member of the discharge wire, and a resistance value of a heating part that generates heat in a region relatively far from the support member. The charger according to claim 1, wherein the charger is formed to be large. A discharge wire heating power source for generating heat by passing a current through the discharge wire;
3. The charger according to claim 1, wherein the discharge wire includes a region having a spiral shape in the vicinity of the support member, and a region having a linear shape relatively far from the support member.   The heating wire has a heating part that generates heat in the vicinity of an area relatively close to the support member of the discharge wire and a surface of the heating part that generates heat in an area relatively far from the support member of the discharge wire. The charger according to any one of claims 1 to 3, wherein the charger is coated with a catalyst material layer that decomposes a substance generated by discharge.   The charger according to any one of claims 1 to 4, wherein a surface of the discharge wire is coated with a catalyst material layer that decomposes a substance generated by discharge.   The charger according to any one of claims 1 to 5, wherein an inner surface of a shield case covering the discharge wire is covered with a catalyst material layer that decomposes a substance generated by discharge. An image forming apparatus comprising the charger according to claim 1 .

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